The invention relates to devices for inserting a needle or the like into tissue, and to methods of making and using such devices. More particularly, it relates to an insertion device for inserting an injection needle into a tissue, more particularly wherein the insertion device is part of a catheter head, and, more particularly, wherein the catheter head is part of an infusion set.
Many different types of insertion devices for inserting an injection needle into a tissue are known in the prior art. In addition to having a needle holder from which the injection needle protrudes, more recent insertion devices also comprise a protection device for protecting and/or covering the injection needle after withdrawal from the tissue. The protection device serves to protect the person using the insertion device from needle-stick injuries, as the injection needle is freely accessible after withdrawal from the tissue. Such insertion devices are used in various medical or therapeutic devices and procedures in which an active fluid substance or another liquid has to be introduced into a body tissue.
Insertion devices have been used for catheter heads for, for example, infusion sets. The catheter head serves as port for introducing a liquid active substance, e.g., insulin, growth hormones. etc., into the body tissue. For this purpose, the catheter head is applied for a considerable length of time on the surface of the body tissue. A flexible cannula protrudes from an underside of the catheter head into the body tissue. Because of its flexibility, the cannula can follow the movements and changes of the body tissue and thus causes as little discomfort as possible for the person using the catheter head. Above the tissue surface, a catheter leads from the catheter head to a receptacle containing the liquid active substance. The catheter is in fluidic communication with the cannula. For introducing the flexible cannula into the body tissue, a rigid injection needle can be used which, for example, is guided through the cannula such that the latter bears firmly on the injection needle, and whose insertion tip protrudes beyond the cannula. After the cannula has been introduced into the tissue, the rigid injection needle is pulled from the cannula, said cannula remaining in the tissue. The injection needle accordingly forms an insertion aid for the flexible cannula.
An insertion device with an injection needle as insertion aid for a catheter head as described above is described in WO 00/03757. The insertion device has a housing from which an injection needle protrudes in such a way that it reaches through a base body of the catheter head and extends through the flexible cannula of the catheter head. Arranged on one side of the housing of the insertion device, there is a protection device in the form of a sleeve cap which is pivotable relative to the housing and which is open at one end in the direction of the needle. In a first state for insertion of the injection needle, the sleeve cap protrudes from the housing perpendicularly with respect to the needle axis. After insertion of the injection needle, or flexible cannula, the insertion device is detached from the base body of the catheter head, the injection needle being withdrawn from the tissue or the flexible cannula. After the withdrawal of the insertion device, the sleeve cap can then be pivoted relative to the housing and over the injection needle. In doing this, the injection needle is bent sideways in the pivoting direction of the sleeve cap and is partially surrounded by the latter. On that side of the housing opposite from the sleeve cap, catch devices are provided in which the sleeve cap engages after pivoting, in such a way that it is not pivoted back by the restoring force of the bent needle. However, after withdrawal from the tissue or from the base body of the catheter head, the injection needle is initially exposed, as a result of which there is a risk of injury to the user. Moreover, the sleeve cap has to be guided manually over the injection needle, as a result of which there is an additional risk of injury because various maneuvers have to be performed in the vicinity of the injection needle.